NOAO >   Observing Info >   Approved Programs >   2006A-0467

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Proposal Information for 2006A-0467


PI: Taro Sato, University of California, Santa Barbara, taro@physics.ucsb.edu
Address: Department of Physics, Broida Hall, Building 572, Santa Barbara, CA 93106-9530, U.S.A.

CoI: Crystal L. Martin, University of California, Santa Barbara

Title: Near-Infrared Imaging of Infalling Galaxies in Abell 851

Abstract: Recent observations indicate the transformation of galaxies begins well beyond cluster virial radii, i.e., in infall regions. Since galaxy cluster environment samples a wide range of local environments, the dominant physical process driving the transformation may vary over the infall period. Recent simulations indicate dwarf galaxies respond strongly to tidal perturbations; an important aide in identifying the dominant physical mechanism for galaxy evolution is the differential response of dwarf and giant galaxies to cluster tidal fields and impulsive encounters with other galaxies. Previous cluster galaxy surveys have focused exclusively on the population of massive galaxies. This thesis compares the transformation of dwarf galaxies to that of massive galaxies in Abell 851 (Cl0939+4713; z ~eq 0.4). We have analyzed more than 300 Keck LRIS and DEIMOS spectra of cluster [OII] emitters of which a majority is fainter than the magnitude limit of most recent studies at intermediate redshifts. The composite spectra from our sample show dwarf galaxies may have environment-dependent star formation history (SFH). We request near-infrared (NIR) imaging suitable for stellar mass mapping of cluster galaxies. As a resubmission of NOAO 2004B/0400 proposal to compensate for poor weather, we request 6 nights of KPNO-4m/FLAMINGOS time for wide-field imaging between 01 February and 19 February of 2006 or time up to a month outside of this window. The wide-field NIR images will provide a better constraint for underlying stellar mass of faint [OII] emitters as well as the general cluster galaxy population. The optical-NIR colors may also be used to investigate the nature of faint dusty starburst galaxies abundant in this cluster, which appear to arise at the expense of regular star-forming galaxies.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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